Steam-boiler.



No. 65|,269. Patented :une 5, |900.

H. c. PLATTs L T. LAwTHER. f

STEAM BOILER.

(Application led June 29, 1899.)

(No Model.) 3 Sheets-Sheet l.

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H. c. PLATTs & T. LAwTHEn.

STEAM BOILER.

(Application Bled Juno 29, 1899.)

. 3 Sheds-Sheet 2.

(No Model.)

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vNo. 65|,269. Patented lune 5, |900.

y H. C. PLATTS & T. LAWTHEH.

STEAM BILER.4

(Application Bled June 29, 1899.)

3 Sheets-Sheet 3.

L (No Model.)

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NITED STATEs PATENT FFICE,

IIENRY CHARLES PLATTS AND THOMAS LAVTHER, OF LONDON,ENGLAND.

STEAM-BOILER.

SPECIFICATION forming part of Letters Patent N o. 651,269-, dated June 5, 1900.

Application led June 29, 1899.

To all whom t may concern/f Be it known that we, HENRY CHARLES A PLATTs and THOMAS LAWTHER, subjects of the Queen of Great Britain and Ireland, residing at Lime street, London, England, have invented Improvements in Steam-Boilers, of which the following is a specification.

This invention has reference to steam-boilers of the kind in which there are located within the water-containing shell of the boiler a furnace tube or flue, or more than one, containing the re grate or grates and one or more` other tubes or iues through which the products of combustion and hot gases after leaving the furnace or furnaces return to or toward the front of the boiler; and our object is to so construct and arrange such boilers as to improve the water circulation therein and to utilize the gases flowing through the return fiue or iues and whose temperature is lower than that of the products of combustion and gases within the furnace liue or flues for imparting heat to the cooler Water within the boiler instead of allowing said products of combustion and gases to pass, as heretofore usual, through parts of the boiler (and especially those parts immediately above the furnace iiue or flues) containing more highlyheated Water, whose temperature is liable to become thereby lowered rather than raised in consequence of the water surrounding the return flue or liues sometimes havinga higher temperature than the products of combustion and hot gases passing therethrough.

In carrying out this invention the furnace tube or iiue (hereinafter called the furnace- Iiue) or each of them, if there be more than one, and the return tube or iiue or return tubes or iiues (hereinafter called the return flue or fines) is or are so relatively arranged within the shell of the boiler that the return flue or flues shall not be, as is usual,

above, or to a large extent above, the furnace liue or Iiues, andvconsequently in the hottest parts of the'boiler, but wholly or mainly either at one or b oth sides of or below or at one or both sides of v and below the highest part or parts of the furnace flue or tlues7 the arrangement being such that the water in contact with the return flue or tlues shall be the lessheated portions of the water inthe boiler and such as will usually on coming into contact Serial No. 722,294. (No modelwith the wall or walls of the return flue or flues be at a lower temperature than the products of combustion and hot gases then passing through the return flue or fiues.

When one or more return-hues of large diameter or width is or are employed, we sometimes arrange within it or them other vtubes open at their ends to the water-space of the boiler, so that water circulating through these tubes may have its temperature raised by line with a return-.flue at each side provided with curved Water-tubes. Fig. 2 shows a horizontal section of same on the line y y of Fig. 1. Fig. 3 shows a cross-.section of a modified construction in which the furnaceflue occupies a lower position in'the shell. Fig. 4 shows a similar View of another modified construction comprising one furnace-flue and to one side thereof one return-flue. Fig. 5 shows a similar view of another modified construction comprising two furnace-fines, one cylindrical return-flue, and the curved return-fines.

In all the examples like parts where they occur are marked with the same referenceletters.

Referring to Figs.. l and 2, a is a cylindrical outer shellwithin which there is concentrically placed a cylindrical furnace-flue b, corrugated or not, and having within ita grate or grates c, with the necessary bridge d, or bridges, said shell being, as well understood, set in suitable brickwork e, with appropriate fiues, such asf, leading to a chimney g. Within the annular space h between the exterior of the furnace-flue b and the inner surface of the shell a there are provided at two opposite sides of the boileracouple of return-fines c', whose upper and lower ends j constitute IOO tube-plates, which in the example are in 2 6mes planes radiating from the axisof the furnaceiiue, (though this direction is not in all cases essential,) while the outer and inner walls of the said return-fines constitute arcs of circles whereof the axis of the furnace-flue is or may be the center. The upper tube-plate y' of` each return-fine t' is at its highest part not above the level of the highest part of the fu rnace-flue b. Within the return-fines t' there are water-circulating tubes 7s, whose ends are suitably Iixed in the respective tube-platesj of those flucs, these water-tubes 7c having their axes in circular arcs struck (in the example) from the axis of the furnace tube or flue b. The distance apart of the two top tube-plates j is made greater than the length of the longest watertubes 7s, so that such tubes can when necessary be moved into the space between the said tube-plates and then be withdrawn through a manhole in the top ofthe boiler-shell. The return-fines z' may be suitably7 stayed to the furnace-flue Z) and to the shell of the boiler. In the example shown they are simply stayed or stiffened by stays Z of T-section, but other suitable stays maybe substituted. Products of combustion and hot gases from fuel on the grate c pass along the furnace-flue l) to the space or chamber n, thence dividing and passing` in the reverse direction partly through each of the side return-lines t', in passing through which the hot gases impinge upon the tubes 7a,there by imparting heat to water therein which circulates through said tubes toward other parts of the boiler, cooler water from the lower parts of the boiler ascending within said tubes to replace that which passes out at their up-V per ends. stead of being curved and connecting the top and bottom of each flue may be straight and arranged to connect the sides of the iiue, as shown in dotted lines in Fig'. l, such tubes then serving also as stays to the sides of the iiue. Thus it will be seen that by our invention 'we are enabled to utilize to the best advantage products of combustion and hot gases that have already imparted some of their heat to water in higher parts of the boiler during their passage through the furnace-flue ZJ, because we apply these now comparatively less heated gases in parts of the boiler where, as is well known, the temperature of the water is lower than it is in immediate proximity to those parts of the furnace-Hue against which the products of combustion and hot gases in the first instance more directly act.

As will be evident, this principle of construction of boilers, according to which the the example illustrated in Figs. 1 and 2 the details of the boiler itself and of its setting The water-circulating tubes k inmay be varied, the cross-sectional form of the return-fines might be more or less altered, and also the number, form, and direction of the water-tubes,which in some cases might even be dispensed with.

According to the modification represented in Fig. 3 the furnace-flue l) is so' fixed within a cylindrical shell a that the axis of said flue is below that of the shell, and at the respective sides there are provided between the furnace tube or iiue l) and the shellct return-flues t', whose upper and lower ends j are shown in planes radiating from the axis of theshell, (though this direction is not essential.) The inner Walls of these flues are circular arcs struck from the axis, or approximately so', of the furnace tube or flue I), and their outer walls are circular arcs struck from thea'xis, or approximately so, of the shell ct. Vt'ithin these return-lines t' water-circulating tubes are sometimes fixed, but none are shown in Fig. 3.

Instead of providing return-fines such as just referred to at each side of the furnaceiiue b we sometimes (see Fig. 4) arrange the said flue b with its axis in a horizontal plane below that containing the axis of the shell a and in a vertical plane to one side `of that passing through the shells axis, and we provide at one side of the so-arranged furnaceflue b a return-liuc ft', in which there are o1' are not fixed tubes 7s for the circulation of water. f

In one construction of boiler (see Fig. 5) containing two cylindricalplain or corrugated furnace-dues b, having their axes in a common horizontal plane above that containing the axis of the shell a, we provide three re.- turn-fiues t`-viz., a cylindrical return-liue having its axis in the vertical planecontain-l ing that of the shell ct,but located below the furnace-fines b, and two side fines, Whose inner and outer walls are in circular arcs struck from the axis, or approximately so, of the shell Ct.

The return-[lues t' may be made of plain metal or of metal corrugated transversely to the length of the flue or lues or provided with stiffening-rings or equivalent devices. When the return-fines are not provided with water-circulating tubes, the top and bottom Iplates of such flue or ues may beof `curved section.

In other ways the details of construction may be more or less varied withoutdeparting from the characteristic features of the invention. In particular Vit is to be noted that we do not limit ourselves to furnaces of circular form in cross-section, as our invention may be equally embodied in the construction of steam-boilers having furnaces, iiues, and combustion-chambers of various other cross-sectional forms, and these may be arranged in any convenient way so long as the return-lines be caused to pass through the cooler parts of the boiler instead of the hotter parts, as is usual in practice.

IOS

What we claim isl. A steam-boiler comprising a longitudinal shell, one or more main furnace-dues extending longitudinally therethrough, one or more longitudinal return-lues of segmental cross-section located between the main tlue or fines and the adjacent side of said shell, and Water-tubes extending across said return ilue or lues as' set forth.

2. A steam-boiler comprising a longitudinal shell, one or more furnace-dues extenda ing longitudinally therethrough, and one or more longitudinal return-nues of segmental cross-section located between the main line or lues and the adjacent side of said shell, said return flue or lues being arranged below the highest part of said' main flue or iiues as set forth. s

3. A steam-boiler comprising a longitudinal shell, a main furnace-flue extending longitudinally therethrough, a longitudinal returnstlue of segmental cross-section located between the main i'lue and one side ot said shell, and water-tubes extending across said the circular distance between the top tube'- plates of the two return-fines being greater than the length of the longest water-tubes,

.substantially as described for the purpbse specified.

Signed at 77 Cornhill, in the city of London, England, this 3d day of June, 1899.

' lHENRY CHARLES PLATTS.

THOMAS LAWTHER.

Witnesses:

EDMUND S. SNEWIN, WM. O. BROWN. 

